Effect of Sodium Alginate on Non-Specific Immune Parameters and Resistance to Ozone Toxicity in Rainbow Trout Fingerlings (Oncorhynchus mykiss)

Sodium alginate, an anionic polysaccharide, is now considered a new prebiotic due to its immune-stimulating and growth-promoting properties. This study has investigated the effects of sodium alginate on non-specific immune system parameters and growth performance in the rainbow trout fingerling. For these purposes, 90 rainbow trout (3±0.3 g) were fed 3% of body weight with a diet that contain 2.5 g/kg sodium alginate for 45 days. The growth factors and non-specific immune system parameters includes lysozyme, Alternative complement activity (ACH50), bactericidal and respiratory burst activity were investigated in days 15 and 45. At the end of the rearing period, treatments exposed to the toxic dose of ozone. The results showed that the fish feed with diet contain sodium alginate had not significant differences with control treatment on body weight gain, food conversion factor, specific growth rate, condition factor (P>0.05) but there was significant differences in final weight gain (p < 0.05). On both days, 15 and 45, sodium alginate caused the significant increase in lysozyme activity, alternative complement activity, respiratory burst activity and bactericidal of rainbow trout compared to the control treatment (p < 0.05). Furthermore, when the treatments exposed to toxic dose of the ozone, sodium alginate increased relative percent survival compared to the control treatment. According to the results, using of the sodium alginate in diet improved the performance of the  immune system, increased the fish's resistance to the toxic level of ozone and finally increased the relative percent survival in rainbow trout fingerling.